The present invention relates to dialysis cells. Further, the invention relates to a disposable dialysis cell that is economical to manufacture and easy to use. The dialysis cell of the present invention relates to devices for the dialysis of small, fixed-volume samples commonly dialysized in research laboratories. To this end, the device relates to cells which facilitate loading and unloading of samples in a laboratory setting where many specimens are concurrently analyzed.
The early method for the measurement of free thyroxine in serum involved dialysis to separate the free form of the thyroxine from the protein bound form. The partitioning of thyroxine between the free thyroxine and bound thyroxine was estimated by the addition of radio-iodine labeled thyroxine to the serum sample prior to dialysis. The dialysis was carried out by using a diluted serum sample and/or a great excess of dialysate volume to assist in controlling pH.
An improved method for measurement of free thyroxine was described in U.S. Pat. No. 4,963,256 issued to Jerald Nelson. This reference describes a dialysis cell which allows for a direct measurement of free thyroxine by radioimmunoassay which avoids the addition of radio-iodine labeled thyroxine tracers. The dialysis cell is constructed to allow for dialysis of a small volume of buffer against a large volume of a serum sample. At the completion of dialysis, the sample is withdrawn utilizing a pipet for introduction into an RIA tube.
The Nelson dialysis cell has three major parts including a dialysate vial, a membrane cylinder and a cap. The dialysis membrane separates the retentate compartment above a dialysate compartment. Dialysate buffer is introduced into the dialysis chamber, and a serum specimen is introduced into an inner cylinder which is concentrically positioned within the dialysis cell. The Nelson dialysis cell takes advantage of the fact that it has been known that molecules of various molecular weights can be separated across a semi-permeable membrane. The membrane, by virtue of its composition and consequently its porosity, allows molecules of less than a particular molecular weight to pass through the membrane. Larger molecules are unable to pass through the membrane.
Unfortunately, the Nelson dialysis cell has a complicated construction and is difficult to use. Moreover, after introduction of the buffer into the interior chamber, the dialysis cell must be manipulated in which the inner cylinder must be introduced into the cell. It would be advantageous if the dialysis cell did not need to be manually manipulated in such a manner.
Thus, there is a need for an improved dialysis cell which is easy to use.
It would also be desirable to provide a dialysis cell which was inexpensive to manufacture.
Furthermore, it would be highly advantageous to provide a dialysis cell which can be utilized within a tray storing many cells for use within a laboratory environment.